CN1203637C - Time gap CDMA system noise space concerned characteristics estimating method - Google Patents

Abstract

The present invention discloses a noise space correlation characteristic estimation method for a time slot CDMA system, which belongs to the technical field of mobile communication. The method mainly comprises the following steps: channel estimation is carried out for receiving signals, and original channel estimation results are obtained; the original channel estimation results are processed according to a signal-to-noise ratio threshold or an energy ranking method, and a noise response matrix of an aerial array is obtained; the noise response of the aerial array is used for doing correlation calculation, and obtains a spatial correlation matrix of noise. The present invention utilizes channel estimation characteristics of the time slot CDMA system, and gives the noise space characteristic estimation method for a time slot CDMA system. The method is simple and effective, has favorable numerical stability, and gives favorable estimated performance in practical signal-to-noise ratio ranges of the system.

Description

Slot CDMA system spatial noise correlation properties method of estimation

Technical field

What the present invention relates to is a kind of slot CDMA system spatial noise correlation properties method of estimation, and particularly a kind of spatial noise characteristic estimating method that adopts the slot CDMA system of multiaerial system belongs to the mobile communication technology field.

Background technology

Adopt the multiaerial system technology can greatly improve the performance of wireless communication system.If in when multiaerial system empty, handling, not only consider the spatial character of this cell signal, and consider the spatial character of other cell interfering signal, the performance of system is further improved.Realize that the above-mentioned prerequisite of handling when empty is to measure and the spatial correlation characteristic of estimating noise (comprising thermal noise and interference), promptly provides the spatial correlation matrix of noise.The author who publishes in February nineteen ninety-five is P.Jung, the effect and the characteristic of spatial noise correlation matrix in the slot CDMA system that adopts smart antenna have been discussed in the pertinent literature of J.Blanz " Joint Detection withCoherent Receiver Antenna Diversity in CDMA Mobile Radio Systems (joint-detection that adopts relevant antenna diversity to receive in the CDMA mobile communication systems) IEEE Trans.Veh.Tech.; vol.44, pp.76-88 ".But the technology of the document has only been done the situation of hypothesis noise uncorrelated mutually (promptly not considering the noise correlation properties) when realization and emulation, also do not provide the measurement and the method for estimation of spatial noise correlation matrix.In actual applications, wait to ask signal and noise to be superimposed, i.e. e=s+n.Wherein, e is total received signal, the s signal component, and n is a noise component(s).When the correlation properties of actual measurement and estimating noise, common way is that the hypothesis noise is a Gaussian Profile and uncorrelated mutually with signal.Under this condition, have:

E{n·n ^*T}＝E{e·e ^*T}-E{s·s ^*T}

Analysis and simulation result show that all above-mentioned spatial noise correlation matrix estimation algorithm is very unstable when signal to noise ratio increases, and cause the severe exacerbation of error rate of system performance.In the signal to noise ratio scope of practicality, above the performance of described algorithm for estimating can not satisfy the requirement of system.

Summary of the invention

The objective of the invention is to overcome deficiency of the prior art, propose a kind of slot CDMA system spatial noise correlation properties method of estimation, spatial noise correlation matrix estimation algorithm also can be stablized when signal to noise ratio increases and do not cause the deterioration of error rate of system performance.Thereby in the signal to noise ratio scope of practicality, satisfy the requirement of systematic function.

The present invention realizes that according to following technical scheme method of the present invention mainly comprises the steps:

Step a. carries out channel estimating to received signal, obtains original channel estimation results;

Step b. handles original estimation result according to signal-noise ratio threshold or energy ordering method, obtains the noise response matrix of aerial array;

Step c carries out related calculation with the noise response matrix of aerial array and obtains the spatial correlation matrix of noise.

The present invention utilizes the characteristics of slot CDMA system channel estimating, has provided a kind of method of estimation of slot CDMA system spatial noise characteristic.This method is simply effective, has good numerical stability, provides good estimated performance in the signal to noise ratio scope of system's practicality.

Description of drawings

Fig. 1 the inventive method flow chart

Embodiment

As shown in Figure 1, method of the present invention specifically comprises the steps:

Step a. carries out channel estimating to received signal, obtains original channel estimation results.The baseline results of note channel estimating is h ":

h″＝(h″ ⁽¹⁾，h″ ⁽²⁾，Λ，h″ ^(ka)，Λ，h″ ^(Ka)) ^T

H wherein " ^(ka)Be the channel estimating of ka antenna receiving signal:

$h^{\′\′\left(\mathrm{ka}\right)}={(h_1^{\′\′\left(\mathrm{ka}\right)},h_2^{\′\′\left(\mathrm{ka}\right)},\mathrm{\Λ},h_P^{\′\′\left(\mathrm{ka}\right)})}^T$

H wherein _i" ^(ka)Be the value that ka antenna upper signal channel estimated i tap, P is the cycle of used channel estimating basic code.

Step b. handles original estimation result, obtains the noise response matrix of aerial array.Concrete grammar is as follows:

At first the processing that original channel is estimated can be adopted signal-noise ratio threshold method or energy ordering method.The method that signal-noise ratio threshold is handled is: the tap zero setting that is lower than thresholding in the original estimation result.The channel estimating h ' that handles through signal-noise ratio threshold and the baseline results of channel estimating are h " between the pass be:

Wherein, Γ _CHE ²Threshold value for default.Remember that the tap number that each antenna upper signal channel estimation keeps is P ₁The method that energy ordering is handled is: only keep several bigger taps of energy in the channel response, and all the other tap zero setting.Tap number of default is P ₁(0＜P ₁＜P), the energy of channel response is sorted, obtain the wherein bigger P of energy thus ₁The position number of individual tap is: { i ₁, i ₂..., i _P1.The channel estimating h ' that handles through energy ordering and the baseline results of channel estimating are h " between the pass be:

After treatment channel estimating of note is h ' then, and above-mentioned two channel estimation results are subtracted each other, only contained noise and zero noise response matrix N ':

N′＝h″-h′

Step c carries out related calculation with the noise response matrix of aerial array and obtains the spatial correlation matrix of noise.Note spatial noise correlation matrix R _NS, concrete computational methods are:

$R_{\mathrm{ns}}=\frac{N^{\′}*N^{\′H}}{L_{1}D}$

Wherein, H represents to grip altogether transposition, L ₁=P-P ₁, D is the noise penalty factor of channel estimation method.

Claims (7)

1. a slot CDMA system spatial noise correlation properties method of estimation is characterized in that mainly comprising the steps:

Step a. carries out channel estimating to received signal, obtains original channel estimation results;

Step b. handles original estimation result according to signal-noise ratio threshold or energy ordering method, obtains the noise response matrix of aerial array;

Step c carries out related calculation with the noise response matrix of aerial array and obtains the spatial correlation matrix of noise.

2. this slot CDMA system spatial noise correlation properties method of estimation according to claim 1 is characterized in that, carries out channel estimating at first to received signal, obtains original channel estimation results, and the baseline results of note channel estimating is h ":

h″＝(h″ ⁽¹⁾，h″ ⁽²⁾，Λ，h″ ^(ka)，Λ，h″ ^(Ka)) ^T

H wherein " ^(ka)Be the channel estimating of ka antenna receiving signal:

$h^{\′\′\left(\mathrm{ka}\right)}={(h_1^{\′\′\left(\mathrm{ka}\right)},h_2^{\′\′\left(\mathrm{ka}\right)},\mathrm{\Λ},h_P^{\′\′\left(\mathrm{ka}\right)})}^T$

Ht wherein " ^(ka)Be the value that ka antenna upper signal channel estimated i tap, P is the cycle of used channel estimating basic code.

3. this slot CDMA system spatial noise correlation properties method of estimation according to claim 2 is characterized in that, signal-noise ratio threshold method or energy ordering method are adopted in the processing of in step b original channel being estimated.

4. this slot CDMA system spatial noise correlation properties method of estimation according to claim 3, it is characterized in that, the method that signal-noise ratio threshold is handled is: the tap zero setting that is lower than thresholding in the original estimation result, and i channel estimation results h that tap is handled through signal-noise ratio threshold on ka the antenna _i' ^(ka)Obtain by following algorithm:

Wherein, Γ _CHE ²Be the threshold value of default, H _i" ^(ka)It is the value that ka antenna upper signal channel estimated i tap;

The channel estimation results h ' that handles through signal-noise ratio threshold is:

h′＝(h′ ⁽¹⁾，h′ ⁽²⁾，Λ，h′ ^(ka)，Λ，h′ ^(Kα)) ^T。

5. this slot CDMA system spatial noise correlation properties method of estimation according to claim 3, it is characterized in that, the method that energy ordering is handled is: only keep several bigger taps of energy in the channel response, and all the other tap zero setting, tap number of default is P ₁, 0＜P ₁＜P sorts to the energy of channel response, obtains the wherein bigger P of energy ₁The position number of individual tap is: { i ₁, i ₂..., i _P1, i channel estimation results h that tap is handled through energy ordering on ka antenna then _i' ^(ka)Obtain by following algorithm:

H wherein _i" ^(ka)It is the value that ka antenna upper signal channel estimated i tap;

Then the channel estimation results h ' that handles through energy ordering is:

h′＝(h′ ⁽¹⁾，h′ ⁽²⁾，Λ，h′ ^(ka)，Λ，h′ ^(Kα)) ^T。

6. according to claim 4 or 5 described this slot CDMA system spatial noise correlation properties methods of estimation, it is characterized in that, is described treated channel estimation results h ' and original channel results estimated h " subtract each other, only contained noise and zero noise response matrix N '.

7. this slot CDMA system spatial noise correlation properties method of estimation according to claim 1 is characterized in that, note spatial noise correlation matrix R _NS, in step c be with the carry out related calculation concrete computational methods of the spatial correlation matrix that obtains noise of the noise response matrix of aerial array:

$R_{\mathrm{ns}}=\frac{N^{\′}*N^{\′H}}{L_{1}D}$

Wherein, H represents to grip altogether transposition, L ₁=P-P ₁, D is the noise penalty factor of channel estimation method.